A new modular motor-modular inverter (MM-MI) concept for medium voltage adjustable speed drive systems

In this paper, a new modular motor-modular inverter (MM-MI) concept for medium voltage adjustable speed drive (MV-ASD) systems is introduced. It is shown that a standard medium voltage motor winding connections can be reconnected into several three-phase groups, each powered by a separate three-phase PWM inverter, resulting in a high performance MV-ASD system. The proposed approach is fault tolerant and can continue to operate at reduced power levels, under inverter and/or motor faults. An example 250 hp, 4 pole, 60 Hz, 2300 V/4160 V motor winding connection diagram along with the associated inverter configurations is analyzed. Results from analysis are presented on the aspects of faults and motor operation under partial winding excitation. Experimental results on a low voltage (460 V), 10 hp ASD are demonstrated.